The present invention relates to a pressure transducer and, more particularly, to a disposable pressure transducer that can be used to measure pressure gradients, relative pressure and mass flow rate.
There are currently a number of disposable pressure transducers on the market, particularly, for the measurement of the blood pressure in a human patient in various hospital environments. Such blood pressure disposable transducers are shown and described in U.S. Pat. Nos. 4,576,181; 4,610,256; 4,679,567 and 5,105,820. As can be seen, such pressure transducers rely upon a special strain gage chip that is positioned within the plastic housing and which is commercially produced for such applications.
In such present blood pressure transducers, typically the chip is positioned between a chamber that sees the blood pressure of the patient to be measured and a chamber that is open to the atmosphere so that the absolute pressure is read by the chip as it flexes due to the changes in the patients blood pressure.
There is a need for a disposable differential pressure transducer since there are many occasions when the difference in pressure between two supra or subatmospheric pressures are involved and a determination needed as to that differential. At the present, such differential pressure transducers are rather expensive and the construction not adapted to the inexpensive, throw-away variety.
In particular, at the present, disposable pressure transducers are used to determine the blood pressure of a patient at two differing locations by running separate lines to the locations where the pressure is to be measured and those lines communicating to a single disposable pressure transducer through a series of stopcocks where either pressure line may be selected. As a continuing problem with such measurements, it is possible to inadvertently misposition the stopcocks such that the pressure transducer is shunted out of the circuit and the two separate locations within the patient are actually connected to each other.
Therefore, there is a need for an inexpensively constructed differential pressure transducer for uses where the difference in two pressure levels is desired, where neither of the pressures need be atmospheric pressure.